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comparison include/llvm/Analysis/SparsePropagation.h @ 121:803732b1fca8

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LLVM 5.0
author kono
date Fri, 27 Oct 2017 17:07:41 +0900
parents 1172e4bd9c6f
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120:1172e4bd9c6f 121:803732b1fca8
13 //===----------------------------------------------------------------------===// 13 //===----------------------------------------------------------------------===//
14 14
15 #ifndef LLVM_ANALYSIS_SPARSEPROPAGATION_H 15 #ifndef LLVM_ANALYSIS_SPARSEPROPAGATION_H
16 #define LLVM_ANALYSIS_SPARSEPROPAGATION_H 16 #define LLVM_ANALYSIS_SPARSEPROPAGATION_H
17 17
18 #include "llvm/ADT/DenseMap.h" 18 #include "llvm/IR/Instructions.h"
19 #include "llvm/ADT/SmallPtrSet.h" 19 #include "llvm/Support/Debug.h"
20 #include "llvm/IR/BasicBlock.h"
21 #include <set> 20 #include <set>
22 #include <vector> 21
22 #define DEBUG_TYPE "sparseprop"
23 23
24 namespace llvm { 24 namespace llvm {
25 class Value; 25
26 class Constant; 26 /// A template for translating between LLVM Values and LatticeKeys. Clients must
27 class Argument; 27 /// provide a specialization of LatticeKeyInfo for their LatticeKey type.
28 class Instruction; 28 template <class LatticeKey> struct LatticeKeyInfo {
29 class PHINode; 29 // static inline Value *getValueFromLatticeKey(LatticeKey Key);
30 class TerminatorInst; 30 // static inline LatticeKey getLatticeKeyFromValue(Value *V);
31 class BasicBlock; 31 };
32 class Function; 32
33 template <class LatticeKey, class LatticeVal,
34 class KeyInfo = LatticeKeyInfo<LatticeKey>>
33 class SparseSolver; 35 class SparseSolver;
34 class raw_ostream;
35
36 template <typename T> class SmallVectorImpl;
37 36
38 /// AbstractLatticeFunction - This class is implemented by the dataflow instance 37 /// AbstractLatticeFunction - This class is implemented by the dataflow instance
39 /// to specify what the lattice values are and how they handle merges etc. 38 /// to specify what the lattice values are and how they handle merges etc. This
40 /// This gives the client the power to compute lattice values from instructions, 39 /// gives the client the power to compute lattice values from instructions,
41 /// constants, etc. The requirement is that lattice values must all fit into 40 /// constants, etc. The current requirement is that lattice values must be
42 /// a void*. If a void* is not sufficient, the implementation should use this 41 /// copyable. At the moment, nothing tries to avoid copying. Additionally,
43 /// pointer to be a pointer into a uniquing set or something. 42 /// lattice keys must be able to be used as keys of a mapping data structure.
44 /// 43 /// Internally, the generic solver currently uses a DenseMap to map lattice keys
45 class AbstractLatticeFunction { 44 /// to lattice values. If the lattice key is a non-standard type, a
46 public: 45 /// specialization of DenseMapInfo must be provided.
47 typedef void *LatticeVal; 46 template <class LatticeKey, class LatticeVal> class AbstractLatticeFunction {
48
49 private: 47 private:
50 LatticeVal UndefVal, OverdefinedVal, UntrackedVal; 48 LatticeVal UndefVal, OverdefinedVal, UntrackedVal;
51 49
52 public: 50 public:
53 AbstractLatticeFunction(LatticeVal undefVal, LatticeVal overdefinedVal, 51 AbstractLatticeFunction(LatticeVal undefVal, LatticeVal overdefinedVal,
54 LatticeVal untrackedVal) { 52 LatticeVal untrackedVal) {
55 UndefVal = undefVal; 53 UndefVal = undefVal;
56 OverdefinedVal = overdefinedVal; 54 OverdefinedVal = overdefinedVal;
57 UntrackedVal = untrackedVal; 55 UntrackedVal = untrackedVal;
58 } 56 }
59 virtual ~AbstractLatticeFunction(); 57
58 virtual ~AbstractLatticeFunction() = default;
60 59
61 LatticeVal getUndefVal() const { return UndefVal; } 60 LatticeVal getUndefVal() const { return UndefVal; }
62 LatticeVal getOverdefinedVal() const { return OverdefinedVal; } 61 LatticeVal getOverdefinedVal() const { return OverdefinedVal; }
63 LatticeVal getUntrackedVal() const { return UntrackedVal; } 62 LatticeVal getUntrackedVal() const { return UntrackedVal; }
64 63
65 /// IsUntrackedValue - If the specified Value is something that is obviously 64 /// IsUntrackedValue - If the specified LatticeKey is obviously uninteresting
66 /// uninteresting to the analysis (and would always return UntrackedVal), 65 /// to the analysis (i.e., it would always return UntrackedVal), this
67 /// this function can return true to avoid pointless work. 66 /// function can return true to avoid pointless work.
68 virtual bool IsUntrackedValue(Value *V) { return false; } 67 virtual bool IsUntrackedValue(LatticeKey Key) { return false; }
69 68
70 /// ComputeConstant - Given a constant value, compute and return a lattice 69 /// ComputeLatticeVal - Compute and return a LatticeVal corresponding to the
71 /// value corresponding to the specified constant. 70 /// given LatticeKey.
72 virtual LatticeVal ComputeConstant(Constant *C) { 71 virtual LatticeVal ComputeLatticeVal(LatticeKey Key) {
73 return getOverdefinedVal(); // always safe 72 return getOverdefinedVal();
74 } 73 }
75 74
76 /// IsSpecialCasedPHI - Given a PHI node, determine whether this PHI node is 75 /// IsSpecialCasedPHI - Given a PHI node, determine whether this PHI node is
77 /// one that the we want to handle through ComputeInstructionState. 76 /// one that the we want to handle through ComputeInstructionState.
78 virtual bool IsSpecialCasedPHI(PHINode *PN) { return false; } 77 virtual bool IsSpecialCasedPHI(PHINode *PN) { return false; }
79
80 /// GetConstant - If the specified lattice value is representable as an LLVM
81 /// constant value, return it. Otherwise return null. The returned value
82 /// must be in the same LLVM type as Val.
83 virtual Constant *GetConstant(LatticeVal LV, Value *Val, SparseSolver &SS) {
84 return nullptr;
85 }
86
87 /// ComputeArgument - Given a formal argument value, compute and return a
88 /// lattice value corresponding to the specified argument.
89 virtual LatticeVal ComputeArgument(Argument *I) {
90 return getOverdefinedVal(); // always safe
91 }
92 78
93 /// MergeValues - Compute and return the merge of the two specified lattice 79 /// MergeValues - Compute and return the merge of the two specified lattice
94 /// values. Merging should only move one direction down the lattice to 80 /// values. Merging should only move one direction down the lattice to
95 /// guarantee convergence (toward overdefined). 81 /// guarantee convergence (toward overdefined).
96 virtual LatticeVal MergeValues(LatticeVal X, LatticeVal Y) { 82 virtual LatticeVal MergeValues(LatticeVal X, LatticeVal Y) {
97 return getOverdefinedVal(); // always safe, never useful. 83 return getOverdefinedVal(); // always safe, never useful.
98 } 84 }
99 85
100 /// ComputeInstructionState - Given an instruction and a vector of its operand 86 /// ComputeInstructionState - Compute the LatticeKeys that change as a result
101 /// values, compute the result value of the instruction. 87 /// of executing instruction \p I. Their associated LatticeVals are store in
102 virtual LatticeVal ComputeInstructionState(Instruction &I, SparseSolver &SS) { 88 /// \p ChangedValues.
103 return getOverdefinedVal(); // always safe, never useful. 89 virtual void
104 } 90 ComputeInstructionState(Instruction &I,
105 91 DenseMap<LatticeKey, LatticeVal> &ChangedValues,
106 /// PrintValue - Render the specified lattice value to the specified stream. 92 SparseSolver<LatticeKey, LatticeVal> &SS) = 0;
107 virtual void PrintValue(LatticeVal V, raw_ostream &OS); 93
94 /// PrintLatticeVal - Render the given LatticeVal to the specified stream.
95 virtual void PrintLatticeVal(LatticeVal LV, raw_ostream &OS);
96
97 /// PrintLatticeKey - Render the given LatticeKey to the specified stream.
98 virtual void PrintLatticeKey(LatticeKey Key, raw_ostream &OS);
99
100 /// GetValueFromLatticeVal - If the given LatticeVal is representable as an
101 /// LLVM value, return it; otherwise, return nullptr. If a type is given, the
102 /// returned value must have the same type. This function is used by the
103 /// generic solver in attempting to resolve branch and switch conditions.
104 virtual Value *GetValueFromLatticeVal(LatticeVal LV, Type *Ty = nullptr) {
105 return nullptr;
106 }
108 }; 107 };
109 108
110 /// SparseSolver - This class is a general purpose solver for Sparse Conditional 109 /// SparseSolver - This class is a general purpose solver for Sparse Conditional
111 /// Propagation with a programmable lattice function. 110 /// Propagation with a programmable lattice function.
112 /// 111 template <class LatticeKey, class LatticeVal, class KeyInfo>
113 class SparseSolver { 112 class SparseSolver {
114 typedef AbstractLatticeFunction::LatticeVal LatticeVal; 113
115 114 /// LatticeFunc - This is the object that knows the lattice and how to
116 /// LatticeFunc - This is the object that knows the lattice and how to do
117 /// compute transfer functions. 115 /// compute transfer functions.
118 AbstractLatticeFunction *LatticeFunc; 116 AbstractLatticeFunction<LatticeKey, LatticeVal> *LatticeFunc;
119 117
120 DenseMap<Value *, LatticeVal> ValueState; // The state each value is in. 118 /// ValueState - Holds the LatticeVals associated with LatticeKeys.
121 SmallPtrSet<BasicBlock *, 16> BBExecutable; // The bbs that are executable. 119 DenseMap<LatticeKey, LatticeVal> ValueState;
122 120
123 std::vector<Instruction *> InstWorkList; // Worklist of insts to process. 121 /// BBExecutable - Holds the basic blocks that are executable.
124 122 SmallPtrSet<BasicBlock *, 16> BBExecutable;
125 std::vector<BasicBlock *> BBWorkList; // The BasicBlock work list 123
124 /// ValueWorkList - Holds values that should be processed.
125 SmallVector<Value *, 64> ValueWorkList;
126
127 /// BBWorkList - Holds basic blocks that should be processed.
128 SmallVector<BasicBlock *, 64> BBWorkList;
129
130 using Edge = std::pair<BasicBlock *, BasicBlock *>;
126 131
127 /// KnownFeasibleEdges - Entries in this set are edges which have already had 132 /// KnownFeasibleEdges - Entries in this set are edges which have already had
128 /// PHI nodes retriggered. 133 /// PHI nodes retriggered.
129 typedef std::pair<BasicBlock*,BasicBlock*> Edge;
130 std::set<Edge> KnownFeasibleEdges; 134 std::set<Edge> KnownFeasibleEdges;
131 135
132 SparseSolver(const SparseSolver&) = delete;
133 void operator=(const SparseSolver&) = delete;
134
135 public: 136 public:
136 explicit SparseSolver(AbstractLatticeFunction *Lattice) 137 explicit SparseSolver(
138 AbstractLatticeFunction<LatticeKey, LatticeVal> *Lattice)
137 : LatticeFunc(Lattice) {} 139 : LatticeFunc(Lattice) {}
138 ~SparseSolver() { delete LatticeFunc; } 140 SparseSolver(const SparseSolver &) = delete;
141 SparseSolver &operator=(const SparseSolver &) = delete;
139 142
140 /// Solve - Solve for constants and executable blocks. 143 /// Solve - Solve for constants and executable blocks.
141 /// 144 void Solve();
142 void Solve(Function &F); 145
143 146 void Print(raw_ostream &OS) const;
144 void Print(Function &F, raw_ostream &OS) const; 147
145 148 /// getExistingValueState - Return the LatticeVal object corresponding to the
146 /// getLatticeState - Return the LatticeVal object that corresponds to the 149 /// given value from the ValueState map. If the value is not in the map,
147 /// value. If an value is not in the map, it is returned as untracked, 150 /// UntrackedVal is returned, unlike the getValueState method.
148 /// unlike the getOrInitValueState method. 151 LatticeVal getExistingValueState(LatticeKey Key) const {
149 LatticeVal getLatticeState(Value *V) const { 152 auto I = ValueState.find(Key);
150 DenseMap<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
151 return I != ValueState.end() ? I->second : LatticeFunc->getUntrackedVal(); 153 return I != ValueState.end() ? I->second : LatticeFunc->getUntrackedVal();
152 } 154 }
153 155
154 /// getOrInitValueState - Return the LatticeVal object that corresponds to the 156 /// getValueState - Return the LatticeVal object corresponding to the given
155 /// value, initializing the value's state if it hasn't been entered into the 157 /// value from the ValueState map. If the value is not in the map, its state
156 /// map yet. This function is necessary because not all values should start 158 /// is initialized.
157 /// out in the underdefined state... Arguments should be overdefined, and 159 LatticeVal getValueState(LatticeKey Key);
158 /// constants should be marked as constants.
159 ///
160 LatticeVal getOrInitValueState(Value *V);
161 160
162 /// isEdgeFeasible - Return true if the control flow edge from the 'From' 161 /// isEdgeFeasible - Return true if the control flow edge from the 'From'
163 /// basic block to the 'To' basic block is currently feasible. If 162 /// basic block to the 'To' basic block is currently feasible. If
164 /// AggressiveUndef is true, then this treats values with unknown lattice 163 /// AggressiveUndef is true, then this treats values with unknown lattice
165 /// values as undefined. This is generally only useful when solving the 164 /// values as undefined. This is generally only useful when solving the
172 /// querying the lattice. 171 /// querying the lattice.
173 bool isBlockExecutable(BasicBlock *BB) const { 172 bool isBlockExecutable(BasicBlock *BB) const {
174 return BBExecutable.count(BB); 173 return BBExecutable.count(BB);
175 } 174 }
176 175
177 private:
178 /// UpdateState - When the state for some instruction is potentially updated,
179 /// this function notices and adds I to the worklist if needed.
180 void UpdateState(Instruction &Inst, LatticeVal V);
181
182 /// MarkBlockExecutable - This method can be used by clients to mark all of 176 /// MarkBlockExecutable - This method can be used by clients to mark all of
183 /// the blocks that are known to be intrinsically live in the processed unit. 177 /// the blocks that are known to be intrinsically live in the processed unit.
184 void MarkBlockExecutable(BasicBlock *BB); 178 void MarkBlockExecutable(BasicBlock *BB);
179
180 private:
181 /// UpdateState - When the state of some LatticeKey is potentially updated to
182 /// the given LatticeVal, this function notices and adds the LLVM value
183 /// corresponding the key to the work list, if needed.
184 void UpdateState(LatticeKey Key, LatticeVal LV);
185 185
186 /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB 186 /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
187 /// work list if it is not already executable. 187 /// work list if it is not already executable.
188 void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest); 188 void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest);
189 189
195 void visitInst(Instruction &I); 195 void visitInst(Instruction &I);
196 void visitPHINode(PHINode &I); 196 void visitPHINode(PHINode &I);
197 void visitTerminatorInst(TerminatorInst &TI); 197 void visitTerminatorInst(TerminatorInst &TI);
198 }; 198 };
199 199
200 //===----------------------------------------------------------------------===//
201 // AbstractLatticeFunction Implementation
202 //===----------------------------------------------------------------------===//
203
204 template <class LatticeKey, class LatticeVal>
205 void AbstractLatticeFunction<LatticeKey, LatticeVal>::PrintLatticeVal(
206 LatticeVal V, raw_ostream &OS) {
207 if (V == UndefVal)
208 OS << "undefined";
209 else if (V == OverdefinedVal)
210 OS << "overdefined";
211 else if (V == UntrackedVal)
212 OS << "untracked";
213 else
214 OS << "unknown lattice value";
215 }
216
217 template <class LatticeKey, class LatticeVal>
218 void AbstractLatticeFunction<LatticeKey, LatticeVal>::PrintLatticeKey(
219 LatticeKey Key, raw_ostream &OS) {
220 OS << "unknown lattice key";
221 }
222
223 //===----------------------------------------------------------------------===//
224 // SparseSolver Implementation
225 //===----------------------------------------------------------------------===//
226
227 template <class LatticeKey, class LatticeVal, class KeyInfo>
228 LatticeVal
229 SparseSolver<LatticeKey, LatticeVal, KeyInfo>::getValueState(LatticeKey Key) {
230 auto I = ValueState.find(Key);
231 if (I != ValueState.end())
232 return I->second; // Common case, in the map
233
234 if (LatticeFunc->IsUntrackedValue(Key))
235 return LatticeFunc->getUntrackedVal();
236 LatticeVal LV = LatticeFunc->ComputeLatticeVal(Key);
237
238 // If this value is untracked, don't add it to the map.
239 if (LV == LatticeFunc->getUntrackedVal())
240 return LV;
241 return ValueState[Key] = LV;
242 }
243
244 template <class LatticeKey, class LatticeVal, class KeyInfo>
245 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::UpdateState(LatticeKey Key,
246 LatticeVal LV) {
247 auto I = ValueState.find(Key);
248 if (I != ValueState.end() && I->second == LV)
249 return; // No change.
250
251 // Update the state of the given LatticeKey and add its corresponding LLVM
252 // value to the work list.
253 ValueState[Key] = LV;
254 if (Value *V = KeyInfo::getValueFromLatticeKey(Key))
255 ValueWorkList.push_back(V);
256 }
257
258 template <class LatticeKey, class LatticeVal, class KeyInfo>
259 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::MarkBlockExecutable(
260 BasicBlock *BB) {
261 if (!BBExecutable.insert(BB).second)
262 return;
263 DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n");
264 BBWorkList.push_back(BB); // Add the block to the work list!
265 }
266
267 template <class LatticeKey, class LatticeVal, class KeyInfo>
268 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::markEdgeExecutable(
269 BasicBlock *Source, BasicBlock *Dest) {
270 if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
271 return; // This edge is already known to be executable!
272
273 DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName() << " -> "
274 << Dest->getName() << "\n");
275
276 if (BBExecutable.count(Dest)) {
277 // The destination is already executable, but we just made an edge
278 // feasible that wasn't before. Revisit the PHI nodes in the block
279 // because they have potentially new operands.
280 for (BasicBlock::iterator I = Dest->begin(); isa<PHINode>(I); ++I)
281 visitPHINode(*cast<PHINode>(I));
282 } else {
283 MarkBlockExecutable(Dest);
284 }
285 }
286
287 template <class LatticeKey, class LatticeVal, class KeyInfo>
288 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::getFeasibleSuccessors(
289 TerminatorInst &TI, SmallVectorImpl<bool> &Succs, bool AggressiveUndef) {
290 Succs.resize(TI.getNumSuccessors());
291 if (TI.getNumSuccessors() == 0)
292 return;
293
294 if (BranchInst *BI = dyn_cast<BranchInst>(&TI)) {
295 if (BI->isUnconditional()) {
296 Succs[0] = true;
297 return;
298 }
299
300 LatticeVal BCValue;
301 if (AggressiveUndef)
302 BCValue =
303 getValueState(KeyInfo::getLatticeKeyFromValue(BI->getCondition()));
304 else
305 BCValue = getExistingValueState(
306 KeyInfo::getLatticeKeyFromValue(BI->getCondition()));
307
308 if (BCValue == LatticeFunc->getOverdefinedVal() ||
309 BCValue == LatticeFunc->getUntrackedVal()) {
310 // Overdefined condition variables can branch either way.
311 Succs[0] = Succs[1] = true;
312 return;
313 }
314
315 // If undefined, neither is feasible yet.
316 if (BCValue == LatticeFunc->getUndefVal())
317 return;
318
319 Constant *C =
320 dyn_cast_or_null<Constant>(LatticeFunc->GetValueFromLatticeVal(
321 BCValue, BI->getCondition()->getType()));
322 if (!C || !isa<ConstantInt>(C)) {
323 // Non-constant values can go either way.
324 Succs[0] = Succs[1] = true;
325 return;
326 }
327
328 // Constant condition variables mean the branch can only go a single way
329 Succs[C->isNullValue()] = true;
330 return;
331 }
332
333 if (TI.isExceptional()) {
334 Succs.assign(Succs.size(), true);
335 return;
336 }
337
338 if (isa<IndirectBrInst>(TI)) {
339 Succs.assign(Succs.size(), true);
340 return;
341 }
342
343 SwitchInst &SI = cast<SwitchInst>(TI);
344 LatticeVal SCValue;
345 if (AggressiveUndef)
346 SCValue = getValueState(KeyInfo::getLatticeKeyFromValue(SI.getCondition()));
347 else
348 SCValue = getExistingValueState(
349 KeyInfo::getLatticeKeyFromValue(SI.getCondition()));
350
351 if (SCValue == LatticeFunc->getOverdefinedVal() ||
352 SCValue == LatticeFunc->getUntrackedVal()) {
353 // All destinations are executable!
354 Succs.assign(TI.getNumSuccessors(), true);
355 return;
356 }
357
358 // If undefined, neither is feasible yet.
359 if (SCValue == LatticeFunc->getUndefVal())
360 return;
361
362 Constant *C = dyn_cast_or_null<Constant>(LatticeFunc->GetValueFromLatticeVal(
363 SCValue, SI.getCondition()->getType()));
364 if (!C || !isa<ConstantInt>(C)) {
365 // All destinations are executable!
366 Succs.assign(TI.getNumSuccessors(), true);
367 return;
368 }
369 SwitchInst::CaseHandle Case = *SI.findCaseValue(cast<ConstantInt>(C));
370 Succs[Case.getSuccessorIndex()] = true;
371 }
372
373 template <class LatticeKey, class LatticeVal, class KeyInfo>
374 bool SparseSolver<LatticeKey, LatticeVal, KeyInfo>::isEdgeFeasible(
375 BasicBlock *From, BasicBlock *To, bool AggressiveUndef) {
376 SmallVector<bool, 16> SuccFeasible;
377 TerminatorInst *TI = From->getTerminator();
378 getFeasibleSuccessors(*TI, SuccFeasible, AggressiveUndef);
379
380 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
381 if (TI->getSuccessor(i) == To && SuccFeasible[i])
382 return true;
383
384 return false;
385 }
386
387 template <class LatticeKey, class LatticeVal, class KeyInfo>
388 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::visitTerminatorInst(
389 TerminatorInst &TI) {
390 SmallVector<bool, 16> SuccFeasible;
391 getFeasibleSuccessors(TI, SuccFeasible, true);
392
393 BasicBlock *BB = TI.getParent();
394
395 // Mark all feasible successors executable...
396 for (unsigned i = 0, e = SuccFeasible.size(); i != e; ++i)
397 if (SuccFeasible[i])
398 markEdgeExecutable(BB, TI.getSuccessor(i));
399 }
400
401 template <class LatticeKey, class LatticeVal, class KeyInfo>
402 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::visitPHINode(PHINode &PN) {
403 // The lattice function may store more information on a PHINode than could be
404 // computed from its incoming values. For example, SSI form stores its sigma
405 // functions as PHINodes with a single incoming value.
406 if (LatticeFunc->IsSpecialCasedPHI(&PN)) {
407 DenseMap<LatticeKey, LatticeVal> ChangedValues;
408 LatticeFunc->ComputeInstructionState(PN, ChangedValues, *this);
409 for (auto &ChangedValue : ChangedValues)
410 if (ChangedValue.second != LatticeFunc->getUntrackedVal())
411 UpdateState(ChangedValue.first, ChangedValue.second);
412 return;
413 }
414
415 LatticeKey Key = KeyInfo::getLatticeKeyFromValue(&PN);
416 LatticeVal PNIV = getValueState(Key);
417 LatticeVal Overdefined = LatticeFunc->getOverdefinedVal();
418
419 // If this value is already overdefined (common) just return.
420 if (PNIV == Overdefined || PNIV == LatticeFunc->getUntrackedVal())
421 return; // Quick exit
422
423 // Super-extra-high-degree PHI nodes are unlikely to ever be interesting,
424 // and slow us down a lot. Just mark them overdefined.
425 if (PN.getNumIncomingValues() > 64) {
426 UpdateState(Key, Overdefined);
427 return;
428 }
429
430 // Look at all of the executable operands of the PHI node. If any of them
431 // are overdefined, the PHI becomes overdefined as well. Otherwise, ask the
432 // transfer function to give us the merge of the incoming values.
433 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
434 // If the edge is not yet known to be feasible, it doesn't impact the PHI.
435 if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent(), true))
436 continue;
437
438 // Merge in this value.
439 LatticeVal OpVal =
440 getValueState(KeyInfo::getLatticeKeyFromValue(PN.getIncomingValue(i)));
441 if (OpVal != PNIV)
442 PNIV = LatticeFunc->MergeValues(PNIV, OpVal);
443
444 if (PNIV == Overdefined)
445 break; // Rest of input values don't matter.
446 }
447
448 // Update the PHI with the compute value, which is the merge of the inputs.
449 UpdateState(Key, PNIV);
450 }
451
452 template <class LatticeKey, class LatticeVal, class KeyInfo>
453 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::visitInst(Instruction &I) {
454 // PHIs are handled by the propagation logic, they are never passed into the
455 // transfer functions.
456 if (PHINode *PN = dyn_cast<PHINode>(&I))
457 return visitPHINode(*PN);
458
459 // Otherwise, ask the transfer function what the result is. If this is
460 // something that we care about, remember it.
461 DenseMap<LatticeKey, LatticeVal> ChangedValues;
462 LatticeFunc->ComputeInstructionState(I, ChangedValues, *this);
463 for (auto &ChangedValue : ChangedValues)
464 if (ChangedValue.second != LatticeFunc->getUntrackedVal())
465 UpdateState(ChangedValue.first, ChangedValue.second);
466
467 if (TerminatorInst *TI = dyn_cast<TerminatorInst>(&I))
468 visitTerminatorInst(*TI);
469 }
470
471 template <class LatticeKey, class LatticeVal, class KeyInfo>
472 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::Solve() {
473 // Process the work lists until they are empty!
474 while (!BBWorkList.empty() || !ValueWorkList.empty()) {
475 // Process the value work list.
476 while (!ValueWorkList.empty()) {
477 Value *V = ValueWorkList.back();
478 ValueWorkList.pop_back();
479
480 DEBUG(dbgs() << "\nPopped off V-WL: " << *V << "\n");
481
482 // "V" got into the work list because it made a transition. See if any
483 // users are both live and in need of updating.
484 for (User *U : V->users())
485 if (Instruction *Inst = dyn_cast<Instruction>(U))
486 if (BBExecutable.count(Inst->getParent())) // Inst is executable?
487 visitInst(*Inst);
488 }
489
490 // Process the basic block work list.
491 while (!BBWorkList.empty()) {
492 BasicBlock *BB = BBWorkList.back();
493 BBWorkList.pop_back();
494
495 DEBUG(dbgs() << "\nPopped off BBWL: " << *BB);
496
497 // Notify all instructions in this basic block that they are newly
498 // executable.
499 for (Instruction &I : *BB)
500 visitInst(I);
501 }
502 }
503 }
504
505 template <class LatticeKey, class LatticeVal, class KeyInfo>
506 void SparseSolver<LatticeKey, LatticeVal, KeyInfo>::Print(
507 raw_ostream &OS) const {
508 if (ValueState.empty())
509 return;
510
511 LatticeKey Key;
512 LatticeVal LV;
513
514 OS << "ValueState:\n";
515 for (auto &Entry : ValueState) {
516 std::tie(Key, LV) = Entry;
517 if (LV == LatticeFunc->getUntrackedVal())
518 continue;
519 OS << "\t";
520 LatticeFunc->PrintLatticeVal(LV, OS);
521 OS << ": ";
522 LatticeFunc->PrintLatticeKey(Key, OS);
523 OS << "\n";
524 }
525 }
200 } // end namespace llvm 526 } // end namespace llvm
201 527
528 #undef DEBUG_TYPE
529
202 #endif // LLVM_ANALYSIS_SPARSEPROPAGATION_H 530 #endif // LLVM_ANALYSIS_SPARSEPROPAGATION_H